<?php
// define array
$cities = array(
  "United Kingdom" => "London",
  "United States" => "Washington",
  "France" => "Paris",
  "India" => null
);

// search array for key
$a =  array_key_exists('India', $cities);
var_dump($a);
var_dump(isset($cities['India']));

// search array for key
$a =  array_key_exists('France', $cities);
var_dump($a);
var_dump(isset($cities['France']));exit;
